Difficult Terrain: overlapping obstacles do not stack

SRD 5.2.1 · Movement

At the table

1. Identify which spaces have an obstacle or condition that makes them Difficult Terrain.
2. Charge one extra foot of movement for every foot moved in those spaces.
3. Apply a separate movement rule, such as climbing, according to that rule’s own wording.

Example decision

Ten feet of a path contains both heavy snow and rubble. No other movement rule applies. What does moving through that ten-foot stretch cost?

20 feet of movement.

Both snow and rubble can make a space Difficult Terrain, but that classification is not cumulative. Each foot costs two feet total, so ten feet costs twenty. If a different rule changes movement in that space, examine it separately; overlapping terrain labels alone do not add another surcharge.

Watch for this mistake

The terrain list distinguishes allies and Tiny creatures from other creatures as obstacles. Do not label every occupied space Difficult Terrain without reading that distinction.

Ask the table

Which spaces are difficult, and is an additional cost coming from a different rule?

Source rule

If a space is Difficult Terrain, every foot of movement in that space costs 1 extra foot. For example, moving 5 feet through Difficult Terrain costs 10 feet of movement. Difficult Terrain isn’t cumulative; either a space is Difficult Terrain or it isn’t. A space is Difficult Terrain if the space contains any of the following or something similar: • A creature that isn’t Tiny or your ally • Furniture that is sized for creatures of your size or larger • Heavy snow, ice, rubble, or undergrowth • Liquid that’s between shin- and waist-deep • A narrow opening sized for a creature one size smaller than you • A slope of 20 degrees or more

Source: SRD 5.2.1, 181. Online guide.